In this investigation, a novel process for hydrogen purification using diffusion-absorption refrigeration cycle and auxiliary nitrogen refrigeration stream is proposed and evaluated. The diffusion-absorption system can provide to a cooling duty of 7.125 kW with a refrigeration temperature of -32.61 °C. Also, the coefficient of performance of this refrigeration cycle is calculated to be 0.424. To drive the refrigeration unit, 16.81 kW of thermal energy is needed. This refrigeration system utilizes ammonia as refrigerant, water as absorbent and helium as inert gas. To generate hydrogen-rich and hydrogen-lean streams, the feed gas stream is separated using the multi-stream heat exchangers, expansion valves, and flash drums. The inlet crude stream consists of H2, CH4, C2H6, C3H8, N2, and C6H6. To increase the pressure of feed stream to 4482 kPa, 63.42 kW of power is consumed by the compressors and air coolers. To develop the integrated process and perform the exergy analysis, the Aspen HYSYS V11 simulator and MATLAB software are utilized, respectively. It was found that the purity of the separated hydrogen stream is about 88%. To evaluate the technical performance of the process, two definitions for the overall exergy efficiency are introduced. The first and second definitions are computed as 93.825% and 35.053%, respectively. Also, the overall exergy destruction rate is found to be 45.764 kW, which about 32% of the irreversibilities occurred in the air cooler as the main component of exergy wasting. Finally, to determine the effective parameters on the system performance, sensitivity analyses are conducted.
|Affiliation of speaker||ITMO University|
|Publication||Журнал "Вестник Международной академии холода"|